- Are there similar close range wireless protocols that are stupid simple (say like IR communications but on Radio spectrum)
- Could someone or some team something stupid that could be handled by todays micro controlers (esp32 is 7€ for a dual core 32bit processor, I suppose it can be used as a dedicated comm. proc)
In a way, wifi is perfect for 0-50m~, we just need a similar idea for 0-10 and low bandwidth.
Another option is ANT+ - that is very low power but also very low bandwidth (8 byte long messages 4x a second ...) protocol used mostly by fitness gear like training bikes, treadmills and such. Many smartphones have radios that are able to use it. Again something that is easy to make work even with an 8bit micro.
For more advanced stuff there is Zigbee, but that is quite a bit more complex (but still manageable even by an 8bit MCU) and there are some licensing issues which kept it rather obscure.
ANT+ could be enough for a control path or maybe keyboard.
I always wanted to try zigbee but it felt too much like a closed world, although people seemed very satisfied with it it seems.
Local radio text chat could also be fun... Think of an IRC channel, only for the people who can grab the signal...